'Canvas - Combing two images, return one img html object?

I have two html img objects with different src urls. I'd like to combine these two images (using canvas), and create one merged img object.

Is this possible? How?

htmlcanvashtml5-canvas


Solution 1:[1]

You can draw both images on the canvas and combine them with any overlay mode you like. To get the bitmap data from the canvas you can use 'toDataURL'. Only note that both images should come from the same domain as the page, otherwise your access to the pixel data is blocked for security reasons.

Solution 2:[2]

You could use drawImage. Demo. Code:

var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");

var img1 = loadImage('http://upload.wikimedia.org/wikipedia/en/2/24/Lenna.png', main);
var img2 = loadImage('http://introcs.cs.princeton.edu/java/31datatype/peppers.jpg', main);

var imagesLoaded = 0;
function main() {
    imagesLoaded += 1;

    if(imagesLoaded == 2) {
        // composite now
        ctx.drawImage(img1, 0, 0);
        
        ctx.globalAlpha = 0.5;
        ctx.drawImage(img2, 0, 0);
    }
}

function loadImage(src, onload) {
    // http://www.thefutureoftheweb.com/blog/image-onload-isnt-being-called
    var img = new Image();
    
    img.onload = onload;
    img.src = src;

    return img;
}

Adapt as needed. :)

Solution 3:[3]

You can find the solution here. Maybe it will help you.

HTML code:

<div id="container">
    <input type="file" id="imageLoader" name="imageLoader" />
    <input type="file" id="iimageLoader" name="imageLoader" />
    <canvas id="imageCanvas" width="300" height="300"></canvas> 
    <a id="lnkDownload" href="#">Save image</a>
</div>

JS code:

var canvas = new fabric.Canvas('imageCanvas', {
  backgroundColor: 'rgb(240,240,240)'
});
canvas.setWidth(300);
canvas.setHeight(300);

var imageLoader = document.getElementById('imageLoader');
imageLoader.addEventListener('change', handleImage, false);

function handleImage(e) {
  var objects = canvas.getObjects();
  for (var i in objects) {
    objects[i].remove();
  }
  var reader = new FileReader();
  reader.onload = function(event) {
    var img = new Image();
    img.onload = function() {
      var imgInstance = new fabric.Image(img, {
        selectable: 1
      })
      canvas.add(imgInstance);
      /* var red = new fabric.Rect({ width: 80, height: 50, fill: 'red'})
      canvas.add(red);
      red.center(); */
      canvas.deactivateAll().renderAll();
    }

    var iimageLoader = document.getElementById('iimageLoader');
    iimageLoader.addEventListener('change', handleImage, false);

    function handleImage(f) {
      var objects = canvas.getObjects();
      /* for (var i in objects) {
        objects[i].remove();
      } */
      var reader = new FileReader();
      reader.onload = function(event) {

        var fimg = new Image();
        fimg.onload = function() {
          var fimgInstance = new fabric.Image(fimg, {
            selectable: 1,
            width: 80,
            height: 50
          })
          canvas.add(fimgInstance);
          fimgInstance.center();
          /* var red = new fabric.Rect({ width: 80, height: 50, fill: 'red'})
          canvas.add(red);
          red.center(); */
          canvas.deactivateAll().renderAll();
        }
        fimg.src = event.target.result;
      }
      reader.readAsDataURL(f.target.files[0]);
    }

    img.src = event.target.result;

  }
  reader.readAsDataURL(e.target.files[0]);
}



var imageSaver = document.getElementById('lnkDownload');
imageSaver.addEventListener('click', saveImage, false);

function saveImage(e,f) {
  this.href = canvas.toDataURL({
    format: 'png',
    quality: 0.8
  });
  this.download = 'canvas.png'
}

I'm using fabric.js as it's more convenient

Solution 4:[4]

You should use the canvas API getImageData() https://developer.mozilla.org/en-US/docs/Web/API/Canvas_API/Tutorial/Pixel_manipulation_with_canvas

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source
Solution 1 Variant
Solution 2 funie200
Solution 3 user18848945
Solution 4 gnerkus

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